JP2001042684A - Fixing device and image recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize the prolongation of service life, even in use of papers having much paper powder and toner requiring a supply of much releasing agent by constituting a release agent coating part of a cleaning part and a release agent supply part, in a roller type fixing device. SOLUTION: In this roller type fixing device 1, the release agent supply part 4 is constituted of a cleaning part having high surface pressure to a fixing roller 2 and a release agent coating part having low surface pressure thereto, and the release agent is supplied to the cleaning part by the release agent coating part. Thus, foreign matter is dammed up by the cleaning part, so that clogging by the release agent coating part is hardly caused and the service life of the fixing device is prolonged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording apparatus for performing printing on a recording medium such as paper or an OHP sheet.
In particular, the present invention relates to a technique for improving the releasability of a toner from a fixing roller of a fixing device that fixes an unfixed toner held on a recording medium based on image data.

[0002]

2. Description of the Related Art In a conventional image recording apparatus, in order to improve the releasability of a toner from a fixing roller of a fixing device for fixing an unfixed toner held on a recording medium based on image data, a fixing device is used. Some include a release agent supply unit that supplies a release agent that supplies a release agent. The release agent supply section (hereinafter, the release agent is also referred to as oil) includes (1) an oil pad method (for example, Japanese Patent Application Laid-Open No. 6-270463),
(2) Oil roller coating method (e.g., JP-A-6-2505)
No. 57) and (3) an oil felt method (for example, Japanese Patent Application Laid-Open No. 5-127666) are known.

[0003] Among them, the prior art (1) has a problem that since the oil is not replenished from the outside, the oil supply amount is greatly reduced when continuous printing is performed, and a long service life (long replacement cycle) cannot be achieved. was there. In addition, there is also a problem that oil streaks are likely to occur due to variations in the oil supply amount of each part.

On the other hand, the prior art (2) is a method in which oil impregnated inside the roller is exuded from a porous layer on the roller surface, and a small amount of oil is applied to the fixing roller to improve the releasability of the toner. However, it is not suitable for toner that consumes a large amount of oil.

[0005] Further, the prior art (3) is a system in which oil is sucked up with felt and exudes oil from a porous body provided on the surface to supply the oil. This method has an advantage that the toner offset to the fixing roller does not easily adhere to the surface of the porous body and can provide a stable oil supply. However, there is a problem that the toner offset to the fixing roller easily slips and stains the recording medium. .

[0006]

The above prior art (1),
Both (2) and (3) can realize oil supply,
(1) and (2) are not suitable for the case where a toner that requires a large amount of oil supply is used in order to ensure releasability from the fixing roller. (3) has the advantage that the amount of oil supply can be determined by setting the pore diameter of the porous body on the surface in terms of structure. However, when there are many foreign matters such as toner and paper powder adhering to the fixing roller, the recording medium There is a problem that dirt easily occurs.

The present invention uses a toner that requires a large amount of oil supply in order to ensure releasability from a fixing roller, and prints without causing stains on a recording medium even when a large amount of foreign matter adheres to the fixing roller. An object of the present invention is to provide a fixing device having a long service life and an image recording apparatus having the fixing device.

[0008]

In order to achieve the above object, a fixing device according to the present invention comprises an oil supply section, a cleaning section which is pressed against a fixing roller at a high surface pressure to block foreign substances, and a low surface section which is fixed to a fixing roller. A porous body that is pressed by pressure and hardly adheres to the surface is composed of an oil application section provided on the surface to make it easier to remove foreign substances, and the cleaning section receives oil supply from the oil application section. Thereby, the fixing roller is hardly damaged.

In the above configuration, since the cleaning unit receives the supply of oil from the oil application unit, the cleaning unit initially functions as an oil supply unit. Foreign matter such as paper dust and toner adhering to the fixing roller due to paper passing is largely clogged by the cleaning unit, and the amount of foreign matter flowing into the oil application unit is reduced. Foreign matter that has flowed into the oil application section has the property that the porous body made of ethylene tetrafluoride resin etc. has a property that it is difficult to adhere to the surface at the oil application section provided on the surface, and it contacts the fixing roller with low surface pressure Therefore, the foreign matter is easily rubbed off and hardly accumulates on the oil-coated portion. For this reason, the oil application section is less likely to be clogged even during paper passing, and can perform stable oil supply.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of the fixing device of the present invention. A fixing roller 2 and a pressure roller 3 having a rubber layer (not shown) made of, for example, silicon rubber on a surface around a metal core (not shown) containing a heater (not shown) are pressed against each other. While the recording medium 16 holding the unfixed toner 17 passes therethrough, heat is transmitted through a flat portion (nip portion) formed between the rubber layers, and the unfixed toner 17 is transferred onto the recording medium 16. Fixation is performed. In such a fixing device, when the adhesive force of the unfixed toner 17 to the fixing roller is larger than the adhesive force of the unfixed toner 17 to the paper, the toner 17 adheres to the surface of the fixing roller 2 and the recording medium 16 is wound around the fixing roller. Oil may be supplied to the surface of the fixing roller 2 from the release agent supply unit 4 in order to avoid this, and the adhesive force between the toner and the fixing roller is reduced. However, in order to prevent the toner that gradually adheres to the fixing roller 2 from deteriorating the application ability of the release agent, in the fixing device of the present invention, in the fixing device of the present invention, the oil application section 39 is attached to the surface of the fibrous felt 7. A porous body 40 made of ethylene tetrafluoride resin or the like is provided to make it difficult for the toner to adhere to the surface of the oil application section, and a felt 5 is formed around the plate member 6 on the upstream side in the rotation direction of the fixing roller 2. The cleaning unit 38 is configured to wind foreign matters such as toner and clogs. The surface pressure distribution of the oil application section 39 and the cleaning section 38 to the fixing roller 2 is as shown at 18b and 18a. The cleaning section is pressed with a high surface pressure, and the oil application section is pressed with a low surface pressure. The reason why the cleaning unit is pressed with a high surface pressure is to dampen foreign matter in front of the cleaning unit, and the case where the oil application unit is pressed with a low surface pressure is to allow the foreign material that has entered there to pass through.

In order to realize this, the cleaning section is fixed to the holder 8a via a rigid leaf spring 9a together with the upper portion of the oil application section (the holder 8a is provided at the contact portion of the porous body 40 with the fixing roller 2). Direct pressure is not applied),
The lower portion of the oil application section is fixed to the holder 8b via a soft leaf spring 9b. The leaf spring 9 is fixed to a base plate 41 inside the oil pan 14. The lower end of the oil application part is in contact with the oil pan 41 and is configured to receive supply of oil from the oil bottle 10. The service life of the release agent supply unit 4 can be extended by providing a rotary cleaning unit 12 for scraping off the toner adhered to the fixing roller 2 upstream of the fixing roller of the release agent supply unit 4. Further, by providing the blade 11 on the downstream side of the fixing roller of the release agent supply unit 4, oil streaks caused by unevenness in the width direction of the release agent supply of the release agent supply unit, which is a problem when printing on OHP or the like, is eliminated. And oil regulations,
Scraping of foreign substances can be realized. Further, the blade can prevent foreign substances from adhering to the paper, and can prevent surface contamination during printing. The pressure roller 3 is provided with a peeling claw 15 to prevent paper from winding around the pressure roller 3. Further, the pressure roller 3 is provided with a cleaning unit 13 so that foreign substances transferred from the fixing roller 2 can be stopped when paper is not passed, thereby preventing back stains during printing.

Here, the structure for pressing the holders 8a and 8b will be described with reference to FIG. The holder 8a that supports the cleaning unit 38 is fixed by a wide and high bending rigid plate spring 9a, and the cleaning unit 38 is pressed against the fixing roller 2 with a large surface pressure. On the other hand, the holder 8b supporting the oil application unit 39 is fixed by a narrow and relatively low bending rigidity plate spring 9b, and is pressed against the fixing roller 2 with a small surface pressure.

Next, a description will be given of the adhesion of foreign substances during paper passing and non-paper passing with reference to FIGS. 3 and 4. FIG. FIG. 3 illustrates foreign matter adhesion during paper passing. In FIG. 3, unfixed toner 17 adheres to the print surface of the recording medium 16 (for example, paper), and paper powder 19 adheres to both surfaces. When the paper passes between the fixing roller 2 and the pressure roller 3, a small amount of toner and paper dust adhere to the fixing roller 2. Most of the toner 17 is the rotary cleaning unit 1.
The paper powder and toner that adhere to the surface 2 and pass through the surface are largely clogged before the cleaning section 38 of the oil supply section, and foreign substances that pass through the section are clogged by the blade 11. Without the blade 11, the slipping toner 20 stains the printed surface, causing image quality degradation.

On the other hand, the adhesion of foreign substances when paper is not passed will be described with reference to FIG. The toner 20 that has passed through the blade 11 among the foreign matters adhering to the fixing roller 2 and other parts while passing the paper.
Is transferred to the pressure roller 3 when paper is not passed, and is stopped by the cleaning unit 13 of the pressure roller. If the cleaning unit 13 of the pressure roller is not provided, the toner 21 transferred to the pressure roller 3 adheres to the back surface of the paper, and becomes the back stain at the time of printing, thereby deteriorating the image quality.

Next, the element characteristics of each part constituting the fixing device will be described with reference to FIG. In the oil application section 39, the horizontal axis represents the oil supply amount of the felt portion 7, and the vertical axis represents the oil supply amount of the porous body. The characteristics were shown for porous materials having three kinds of pore diameters. The larger the pore size, the smaller the difference between the felt oil supply amount and the porous body oil supply amount.

FIG. 6 shows the relationship between the contact width (nip width) between the porous body in the oil application section and the fixing roller and the supply amount of the porous body oil. From this, it is shown that there is almost a proportional relationship between the nip width and the porous body oil supply amount, and if the pore diameter of the porous body and the nip width are determined so that a desired porous body oil supply amount can be obtained. Good.

FIG. 7 shows the relationship between the surface pressure of the oil application portion and the supply amount of the porous oil when the nip width is 5 mm in FIG. This indicates that the oil supply amount is substantially constant regardless of the oil application surface pressure.

FIG. 8 shows the relationship among the surface pressure, the cleaning performance, and the performance of the oil application portion. Since the cleaning unit is required to have foreign matter stopping performance, a sufficient performance is obtained at 0.008 MPa or more when the relationship between the foreign matter stopping performance and the foreign matter stopping performance is examined. On the other hand, in the oil application section, it is difficult for foreign substances to adhere to the porous body (to prevent clogging).
For that reason, when the performance that requires the rubbing performance of foreign matter was examined, it was found that sufficient performance was obtained at 0.005 MPa or less. From the above, it is desirable to set the surface pressure so that the surface pressure of the cleaning unit is 0.008 MPa or more and the surface pressure of the oil application unit is 0.005 MPa or less.

Next, the oil supply performance of the fixing device of the present invention will be described with reference to FIGS. FIG. 9 shows the relationship between the number of sheets passed through the porous body oil supply amount and the oil supply amount after the oil supply amount is regulated by the blade (this oil amount contributes to the release of the toner and the fixing roller). . When the porous body oil supply amount is sufficiently large compared to the blade oil supply amount, the blade oil supply amount is constant, but when the porous body oil supply amount decreases to the same level as the blade oil supply amount, the blade oil supply amount also increases. And the releasability between the toner and the fixing roller may be reduced, and winding may occur. From this, it can be seen that providing an oil supply unit in which the oil supply amount does not decrease with the number of sheets passed is indispensable for producing a long-life fixing device.

Next, the relationship between the supply amount of porous oil and the number of sheets passed with or without the cleaning unit 38 will be described with reference to FIG. As a result, it is possible to realize a long fixing device life with a lower decrease rate of the oil supply amount than with or without the cleaning unit.

Next, the configuration of an image recording apparatus using the fixing device of the present invention will be described with reference to FIG. Drive roller 33,
A photosensitive belt 35 that is vertically stretched by a driven roller 26 also serving as a tension roller that applies tension to the belt and that rotates at a constant speed in the direction of the arrow;
Transfer member 37, which is arranged in contact with
A charging device 27 for uniformly charging the surface of the photoconductor belt 35; an exposure device 24 for exposing the surface of the photoconductor belt 35 uniformly charged to form an electrostatic latent image on the surface; Four developing units 25a, 25b, 25c, and 25d that are arranged so as to be in contact with each other and form a toner image by developing the electrostatic latent image
A paper feed roller 30 for feeding a recording medium from a cassette 23 containing a recording medium 16 such as paper; a registration roller 31 for correcting the orientation of the recording medium fed from the cassette 23; Transfer roller 32 for transferring
A fixing device 1, a paper discharge unit 34 for discharging the fixed recording medium out of the apparatus, an erase lamp 29 for removing electric charges remaining on the surface of the photoreceptor belt 35, and a blade 28 for removing residual toner. And a cleaner 36 for removing toner remaining on the surface of the intermediate transfer member 37 after the transfer.

Next, a method of forming a color image by the present apparatus will be described. After the power is turned on, when a print signal is sent from an information processing device (not shown) to the printer 1 in the print standby state, the exposure device 24 uniformly charges the laser beam corresponding to the toner image by the charger 27 according to the signal. Irradiation is performed on the photoconductor belt 35, and an electrostatic latent image is formed on the photoconductor belt 35.

First, the exposure device 24 is placed on the photosensitive belt 35.
To form an electrostatic latent image corresponding to the yellow toner image, and develop the toner image by the yellow developing unit 25d. Here, 25d is a developing device using yellow toner, 25c is a developing device using magenta toner,
25b is a developing device using cyan toner, 25a is a developing device using black toner, and a developing function is given or lost by controlling a bias voltage to each developing device. I have. Photoreceptor belt 35
The toner image formed thereon is transferred to the surface of the intermediate transfer member 37 at a contact portion with the intermediate transfer member 37, and is held on the surface.

On the other hand, the photosensitive belt 35 after the transfer of the toner image
The upper portion is configured such that after the charge remaining on the surface of the photoreceptor belt 35 is removed by the erase lamp 29, the toner remaining without being transferred is removed by the blade 28.

After the step of returning the surface of the photosensitive belt 35 to the initial state is completed, a magenta toner image of the next color is similarly formed on the surface of the photosensitive belt 35 and held on the surface of the intermediate transfer member 37. The toner image is superimposed on the yellow toner image and transferred onto the intermediate transfer member 37.

The same process is repeated for the cyan and black colors, and the four color toner images are superimposed on the intermediate transfer member 37 and simultaneously held on the surface. In order to transfer the four color toner images formed on the surface of the intermediate transfer body 37 onto the recording medium 16, the sheet feeding roller 30 is rotated to rotate the recording medium 16 stored in the cassette 23 one by one. The recording medium 16 is separated, conveyed to the registration rollers 31, corrected for skew of the recording medium 16, and then stopped.

Next, the rotation of the registration roller 31 is started at a timing such that the registration roller 31 is aligned with the toner image on the intermediate transfer member. At the same time that the leading end of the conveyed recording medium comes into contact with the intermediate transfer body 37, the transfer roller 32 is pressed from the back of the recording medium, and the four color toner images on the surface of the intermediate transfer body 37 are electrostatically transferred onto the recording medium 16 at one time. . Thus, the recording medium 16
The four color toner images formed above are fixed by passing between the fixing roller and the pressure roller of the fixing device 1 and are discharged to the paper discharge unit 34 of the printer 22 to complete a series of printing processes.

By providing the above-described fixing device in such an image recording apparatus, it is possible to use a paper having a large amount of paper dust, have a toner offset, and achieve a long life and stable printing even if foreign matter adheres to the roller. There is an advantage that can be.

[0029]

According to the present invention, it is possible to extend the life of a fixing device including a fixing roller and a pressure roller without significantly reducing the oil supply amount even for paper having a large amount of paper dust. Therefore, even when a toner that requires a large amount of oil to ensure releasability is used, the running cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a fixing device of the present invention.

FIG. 2 is a partial structural view of the fixing device of the present invention.

FIG. 3 is a diagram illustrating an operation of attaching a foreign substance when a sheet is passed by the fixing device of the present invention.

FIG. 4 is a diagram illustrating an operation of attaching a foreign substance when the fixing device of the present invention does not pass a sheet.

FIG. 5 is a diagram illustrating a relationship between a supply amount of felt oil and a supply amount of porous oil in a release agent supply unit of the fixing device of the present invention.

FIG. 6 is a diagram illustrating a relationship between a nip width of an oil application unit and an oil supply amount of a release agent supply unit of the fixing device of the present invention.

FIG. 7 is a diagram illustrating a relationship between a surface pressure of an oil application unit of a release agent supply unit and an oil supply amount of the fixing device of the present invention.

FIG. 8 is a diagram showing the relationship between the surface pressure of the cleaning unit and the oil application unit of the release agent supply unit and the performance of each unit of the fixing device of the present invention.

FIG. 9 is a diagram illustrating a relationship between a supply amount of a release agent of a porous body and a supply amount of a release agent of a blade in the fixing device of the present invention.

FIG. 10 is a diagram illustrating a relationship between an oil supply amount and a number of sheets passed when a cleaning unit is present in a release agent supply unit of the fixing device of the present invention.

FIG. 11 is a diagram showing a configuration of an image recording apparatus of the present invention.

[Explanation of symbols]

1 ... fixing device, 2 ... fixing roller, 3 ... pressure roller, 4 ... release agent supply section, 5 ... cleaning section felt, 6 ... plate member, 7 ... oil application section felt, 8 ... holder, 9 ... board Spring, 10: oil bottle, 11: blade, 12: rotary cleaning member, 13: pressure roller cleaning member, 14 ...
Oil pan, 15 ... peeling nail, 16 ... recording medium, 17 ... toner,
18: surface pressure, 19: paper dust, 20, 21: operation of toner, 22: image recording device, 23: cassette, 24: exposure device, 25: developing device,
26: driven roller, 27: charger, 28: blade, 29: erase lamp, 30: paper feed roller, 31: registration roller, 32
... Transfer roller, 33 ... Drive roller, 34 ... Paper discharge section, 35 ... Photoreceptor belt, 36 ... Cleaner, 37 ... Intermediate transfer body, 38 ... Cleaning section, 39 ... Oil coating section, 40 ... Porous body, 41 ... Base plate, 42 ... Holding plate.

Continuing from the front page (72) Inventor Masaru Nakano 502, Kandate-cho, Tsuchiura-shi, Ibaraki Pref. Machinery Research Laboratories, Hitachi, Ltd. (72) Inventor Katsumi Kumada 1-1-1, Higashitaga-cho, Hitachi City, Ibaraki Prefecture Inside the Electrification Equipment Division, Hitachi, Ltd. (72) Inventor Akira Sasaki 1-1-1, Higashitaga-machi, Hitachi City, Ibaraki Prefecture Co., Ltd. Hitachi, Ltd.Electrical Equipment Division (72) Inventor Takashi Kadohashi 1-1-1, Higashitagacho, Hitachi City, Ibaraki Pref.Hitachi, Ltd.Electrical Equipment Division (72) Inventor Hideki Mayama Higashitagamachi, Hitachi City, Ibaraki Prefecture 1-1-1, Hitachi, Ltd.Electrical Equipment Division (72) Inventor Kazuo Kikuchi 1-1-1, Higashitaga-cho, Hitachi, Ibaraki Pref.Hitachi, Ltd.Electrical Equipment Division (72) Inventor Katsuyoshi Onose 1-1-1 Higashitagacho, Hitachi City, Ibaraki Prefecture F-term (reference) in Hitachi, Ltd. Electrical Equipment Division 2H033 AA08 BA43 BA44 BA45 BA51 BA52 BA54 BA56 BB01 BB28

Claims (6)

[Claims] An unfixed toner image is fixed by passing through a recording medium holding the unfixed toner image. In a fixing device having a release agent supply unit for applying a mold agent, a cleaning member that contacts the release agent supply unit at a high surface pressure with respect to the fixing roller, and a cleaning member that is separate from the cleaning member, and that is formed in the fixing roller rotation direction. And a release agent coating member provided on the downstream side of the cleaning member and in contact with the fixing roller at a relatively low surface pressure with respect to the cleaning member, and having a porous material partially provided on the surface. And a cleaning device configured to receive a release agent from the release agent application member. 2. A fixing device according to claim 1, wherein said cleaning member and said release agent applying member are configured to apply a pressing force by separate pressing force applying means. 3. The fixing device according to claim 1, wherein a plurality of leaf spring members are fixed to the release agent applying member on a base plate fixed to an oil pan, and each leaf spring member has a tip end. Are branched into two, one has a high bending stiffness, the other has a relatively low bending stiffness,
A first holder is connected to a portion having high bending rigidity, a felt of a cleaning member and a release agent application section is fixed to the first holder, and a second holder is provided to a portion having low bending rigidity. Are bonded, the second holder is provided with a felt of a release agent application portion provided with a porous body on the surface, the end of the release agent application member contacts the oil pan, A fixing device having a configuration in which a release agent is supplied from an oil bottle. 4. A fixing device according to claim 1, further comprising a roller-shaped dry cleaning rotating member upstream of the release agent applying member in the fixing roller rotating direction. A fixing device comprising: a release agent regulating member such as a blade on a downstream side in a fixing roller rotation direction; and / or a cleaning member on a pressure roller. 5. The fixing device according to claim 1, wherein the pressing surface pressure of the cleaning member is 0.008 MPa or more, and the surface pressure of the release agent application section is 0. .
A fixing device having a pressure of 005 MPa or less. 6. A means for forming an electrostatic latent image corresponding to an image signal on a photosensitive member, a developing device for supplying toner to develop the electrostatic latent image, and a toner image on the photosensitive member being transferred. An image recording apparatus comprising an intermediate transfer member for transferring a toner image to a recording medium and a fixing device, wherein the fixing device is any one of claims 1, 2, 3, 4, and 5. An image recording apparatus, comprising: a fixing device.